Very difficult to draw any conclusions from anecdotal evidence of what the PRS paid you for different performances/airtime. We've seen three playings (different tracks at different times) on the same radio programme give wildly different payouts. Aoth trad/arr. Same with performances of same song at different live events like festivals. There's no apparent logic to it.

It might seem unfair that you get full royalties on trad as you would if you wrote it yourself, but the downside of singing trad songs is that it's very unlikely that anyone else's performance of the same song will get you anything. (not impossible, if another performer is generous enough to acknowledge your contribution to the version/arrangement they sing)

But we digress...
The point is that re-release and sales of the albums locked up in CM's legal title would, in many cases, result in royalty payments to the artists.

Anahata